Bottom currents and sediment waves on a shallow carbonate shelf, Northern Carnarvon Basin, Australia

摘要: Abstract The modern seafloor of the Australian Northwest Shelf between Exmouth and Dampier was analyzed for large scale sedimentary bedforms on 3D seismic reflection data. Carnarvon MegaSurvey Petroleum Geo-Services (PGS), a merged dataset multiple industrial surveys with total size 49,717 km2, offers an extensive view continental shelf, slope rise Northern Basin. Over shelf two fields sediment waves were observed in water depths 55–130 m, where may be influenced by different processes including internal waves, tides storms. Based dimensions orientations dominant direction approximate strength local bottom currents could estimated. Information grain-size distribution provided auSEABED database allowing classification into sand- or mudwaves. first wave field is positioned northwest Montebello Islands comparatively narrow mainly sand-sized. It most likely formed increased induced diversion tidal flows around islands. second located north Serrurier Bessieres within depression. Local sediments are poorly sorted, containing significant amounts mud gravel addition to sand-sized grains. coarser fraction have been reworked sandwaves cyclone-induced currents. Alternatively, finer form mudwaves shaped less energetic along-slope oriented topographic consist partially carbonate grains such as ooids peloids that shallow during initial stages post glacial sea-level rise. These stranded thus environment than which they redeposited. In fossil examples similar high-energy ramp systems this possible out-of-equilibrium relationship has taken account interpretation depositional environment.